The present invention relates to miniature TV camera inspection devices, and more particularly to an optical viewing port assembly which is hermetically sealable to a camera housing.
This particular assembly was designed for use with a miniature TV camera system which is useful for making underwater nuclear reactor vessel internals inspections. While the assembly was designed for this specific use, it can be used in many inspection or maintenance situations in dark, inaccessible areas that require visual inspection, such as for nuclear steam generators, steam turbines or general piping inspections.
A miniature camera with an overall housing diameter of only 1.25 inch diameter permits visual inspection in very limited areas which may only be accessible through inlet or outlet piping. The quality of the visual display which can be provided for the inspector is of course a function of the line resolution capability of the TV camera and of the quality of the lens or optical system through which the camera views the scene. The quality of the display also depends upon provision of adequate light within the inaccessible viewing environment. The structure which is being viewed or examined may have a low contrast surface or there may be particulate matter suspended in the medium between the camera and the viewed structure. The camera may have to view the structure from several feet away because of obstructions. It is therefore desirable that as high a lighting level as possible be provided. This high lighting level must be produced while maintaining the outside diameter of the camera housing as small as possible to ensure maximum maneuverability and utility for the camera.
A prior art attempts to provide a high lighting level was to position several miniature lamps about the optical axis of the camera. These lamps were of very small diameter and were rated at about one watt per lamp. While these lamps did not block the field of view of the camera, they provided very little light.
High wattage lamps have been attached to the outside of the camera head to provide high lighting levels, but these lamps add to the overall diameter of the camera and thereby limits its use in restricted space.
The prior art also includes the use of a high power lamp mounted axially ahead of the camera on an extended fixture. This lamp is in the camera field of view and typically blocks the center of the picture which is the highest quality image area for the camera.